Replying to BrokenPromise, its somewhat blurry with monsters. For me, I tend to emphasize that the players explore alternate routes to a solution. I want them to feel the weight of their actions, a life saved or spared. Monsters can be sentient and in games like pathfinder they often are. So a creature driven to try and kill the party has its motivations for doing so. Sometimes killing is unavoidable though. As a player Im kind of an asshole to myGM about this because I often want to spare a life rather than murderhobo over an intelligent creature.

You're very right, of course, about the grittiness varying by player. Some people want a lighthearted, strike down badguys disney style game. I dont tend to play with people who enjoy that gory, killing is as easy as slicing bread playstyle because it's kind of immature and doesnt lend to an immersive game. 

Now, rape, and torture. Torture... it feels like sometimes its kinda necessary, depending on whats happening. Its a frequent part of a fantasy setting. Its just rough, you as a gm have to really draw a line between storytelling and sadism. As for rape, its actually happened in a game I was running, and it was a pc committing it. It was handled well, lent an appropriately dark touch to the game, and the character responsible for it was filled out a bit by the act. But... its a touchy subject. It can ruin an entire game, I think.

Maybe the amount of detail you put into the act of killing and its impact shows the maturity of the player and of the game.